1. Field of the Invention
This invention generally relates to rollers on discs of the type employed in spinning frame apparatus.
2. Description of the Related Art
In the textile and fabric industries, spinning frames are widely employed, which use a multiplicity of rollers or disc which are mounted for rotation on shafts, and rotate at high speeds on the order of 10,000-20,000 rpm in yarn processing operations.
Such rollers typically comprise a disc-shaped core body on the periphery of which is deployed a "tire" of synthetic elastomeric material, to provide a bearing surface for contacting the roller with a yarn twist tube.
Due to the extremely high rotational speeds experienced by these rollers in spinning frame operation, it is critically important that the tire be adequately secured to the disc core body, in order that the tire is not "thrown" in operation as a result of centrifugal force exerted thereon.
The problem of maintaining the tire fixedly secured to the core body of the roller high-speed during operation is further exaccerbated by the fact that the physical properties, e.g., specific heat capacities, conductivities, and coefficients of thermal expansion, of the respective core body and tire elements are quite different from one another. As a result, there is present at the interface or juncture of the core body and the tire a substantial differential in thermal properties, which tend to favor separation and throwing of the tire, when the roller has been subjected to high rotational speeds for sustained periods of operation, as a result of frictional heat buildup in the roller and its constituent core body and tire parts.
Inasmuch as it has not been possible to closely match the thermal physical properties of the core body and tire of the roller, since the core body typically is made of aluminum or other metal, and the tire typically is formed of a synthetic elastomeric material, much effort has been focused on improving the means and methods of securing the tire to the core body to minimize the likelihood of tire separation and "throwing" during high-speed operation.
One roller construction which has been employed by the art is shown in FIG. 1 ("PRIOR ART"), which is a partial elevation view, in cross-section, of the edge region of a spinning frame roller 10 in which the core body 12 is formed on its outer peripheral surface 14 with a generally V-shaped groove 16, as shown. In this construction, the tire 18 is formed with a V-shaped protrusion 20 of corresponding shape for mating with the V-shaped groove 16. Between the core body 12 and tire 18 is provided a thin film of an adhesive composition 22.
This roller construction, by virture of the V-shaped groove and V-shaped protrusion of the respective core body and tire elements, provides an increased surface area for bonding, relative to a completely linear interface, and enables the tire to better resist lateral forces which may otherwise tend to displace the tire from the core body in operation.
Nonetheless, the presence of the adhesive introduces a further bonding operation to the manufacture of the roller, and it is frequently difficult to obtain a substantially even thickness of the adhesive medium along the full extent of the bonding surfaces, particularly in the V-shaped groove, where surface tension effects may render it difficult for the adhesive to penetrate into the lower extremity of the groove.
Apart from such difficulties, a major disadvantage of this adhesively bonded construction is the fact that the substantial heat generated in the roller as a result of friction causes degradation and fracturing of many adhesive compositions, thereby promoting the tendency of the tire to be thrown from the core body. Accordingly, it has been common practice to utilize high tensile shear strength adhesives based on cyanoacrylates, due to their rapid fixturing properties and other favorable performance characteristics. Nonetheless, under the high temperature conditions resulting from frictional heat buildup in the roller, the cyanoacrylate adhesives tend to liberate cyanic volatile species, e.g., methyl isocyanate, hydrogen cyanide, and the like, which are of an extremely hazardous and toxic character.
Another roller design which has been employed in the art is shown in FIG. 2 ("PRIOR ART"), as a cross-section, in elevation, of an outer portion of the roller. In this design, the roller 25 comprises a core body 26 having its outer periphery shaped with reentrant cavities 28 and 30 bounded by the respective shoulders 32 and 34 and bulbous extremity 36 of the core body. The tire 38 in this construction may be molded directly onto the outer periphery of the core body. The problem associated with this design is that the radial width (W) of the tire tends to be excessive, with regard to the centrifugal force thereon and the tendency of the tire to be thrown during operation of the roller at high speeds, e.g., in the range of 10,000 to 20,000 rpm.
U.S. Pat. No. 4,964,324 to H. Gassner et al discloses a friction roller which includes an aluminum or aluminum alloy core body which is joined a polyurethane friction ring. A dovetail groove is provided in this friction roller, on a laterally extending top surface (see FIG. 2 of the patent) of the core body. FIGS. 6 and 7 of this patent show a "sideways T" core body projection. The friction ring is made of a resilient plastics material, such as polyurethane of suitable hardness, which is molded onto the ring, preferably under pressure (column 4, lines 27-34).
U.S. Pat. No. 332,998 to C. Coupland discloses a drawing and spinning machine roll which has a dovetail joint on an outer peripheral surface. In this design, the contact elements are in the form of segments which are circumferentially packed around the outer perimeter of the wheel. The contact elements in this roll have a lesser thickness (as measured in the axial direction) than the ribs forming the dovetail joint. The body of the roll is in the form of half-sections, which are joined to one another by bolt and nut assemblies, as shown in FIG. 1 of the patent.
U.S. Pat. No. 3,610,061 to W. H. Holzboog describes an idle or drive wheel which is formed as an assembly from sections which include a driving disc, a clamping disc, and an elastomeric ring. These three elements are sandwiched together, as shown in FIGS. 1-3 of the patent.
U.S. Pat. No. 402,631 to C. M. Thompson discloses a sand reel in which the wear surface is formed of a multiplicity of segments, as shown in FIG. 3 of the patent. Each of the segments is formed with V-shaped recesses to accommodate mating engagement with discs mounted in axial-spaced relationship relative to one another on a central shaft.
U.S. Pat. No. 668,385 to F. W. Morgan discloses a vehicle tire assembly arrangement, in which an outer rubber tire is formed with a dovetail-shaped channel accommodating insertion of a fabric base portion of hour glass shape, which is retained between spaced-apart "tire-clamping members" of the tire, assembly as shown in FIG. 2 of the patent. In another embodiment (FIG. 4 of the patent), the fabric insert includes radiating leaves extending up into the rubber of the tire and firmly embedded therein to retain the tire in position.
U.S. Pat. No. 668,384 to F. W. Morgan discloses a vehicle wheel having wires embedded in portions of the compressed fabric base of a vehicle tire.
U.S. Pat. No. 2,665,521 discloses a toy wheel assembly, in which an outer wheel portion is injection molded from semi-resilient, elastomeric material, following which the body of the wheel is injection molded in the central opening of the tire, utilizing the tire as a part of the mold or die. The cross-section of the wheel assembly (see FIG. 4 of the patent) reveals the wheel body to have side flanges which receive the inner edges of the tire.
It would be a significant advance in the art to provide a roller adaptable for use in a spinning frame, which has improved resistance to throwing of the tire portion thereof during high-speed operation, relative to spinning frame rollers of the prior art.
Accordingly, it is an object of the present invention to provide a spinning frame roller of such type, characterized by a tire with an enhanced retention ability and resistance to being thrown from the core body during rotation of the roller at high speeds.
It is another object of the present invention to provide a spinning frame roller which is of comparatively simple construction, and which can be manufactured in a ready, and relatively inexpensive manner.
It is still another object of the invention to provide a spinning frame wheel which effectively dissipates heat generated during high speed rotation of the roller.
Other objects and advantages of the invention will be more fully apparent from the ensuing disclosure and appended claims.